In recent years, histological observation of a cell in a living body has been brought to attention for its importance in early detection and early diagnostics of cancer.
As an apparatuses enabling histological observation of a cell in a living body, there is proposed an apparatus such as an endoscope or the like capable of performing observation of a desired region existing in a depth direction by using a confocal image, for example.
In addition, as an apparatus enabling histological observation of a cell in a living body, for example, there is proposed an apparatus such as an endoscope or the like capable of performing magnifying observation at a magnification 20 to 100 times higher than an ordinary microscope, in addition to observation at a normal magnification.
An endoscope proposed in Japanese Unexamined Patent Application Publication No. 2004-159924 includes a microscopic observation optical system for performing the magnifying observation and a focus adjustment mechanism for moving a subject side focus position of the microscopic observation optical system, in a distal end of an insertion portion insertable into a subject's body. Therefore, the endoscope is capable of generating a confocal image for observing a cell at a desired region existing in a depth direction with the above-described configuration.
On the other hand, an optical observation probe and an endoscope observation apparatus proposed in Japanese Unexamined Patent Application Publication No. 2004-166913 include normal magnification image pickup means and high magnification image pickup means. Therefore, the optical observation probe and the endoscope observation apparatus are capable of performing normal magnification observation and histological observation, i.e., magnifying observation with respect to a cell at a desired region existing on a surface layer of a living tissue with the above-described configuration.
However, the endoscope proposed in Japanese Unexamined Patent Application Publication No. 2004-159924 has a problem of high cost at the time of manufacturing, because of the complicated configuration for generating a confocal image.
In addition, the optical observation probe and the endoscope observation apparatus proposed in Japanese Unexamined Patent Application Publication No. 2004-166913 have a problem that an observable area is limited to a cell on the surface layer of the living tissue, because of structural difficulty in performing observation of a cell at a desired region existing in a depth direction in the histological observation.
The present invention has been made in view of the above-described points and an object of the present invention is to provide an endoscope enabling observation of a cell at a desired region existing in a depth direction with a configuration simpler than a conventional one.